The objective of this study was to investigate the effects of supplementation of arginine and valine on growth performance and gut health in broilers challenged with E. maxima and fed excess leucine diets. A total of 832 fourteen- day-old Cobb 500 male broilers were randomly allocated to a 2×2×4 factorial arrangement with 4 replicate cages of 12 birds per cage. The main factors were two dose of E.maxima (EM) either challenged (CC) or non-challenged (NC), two Leu levels of either normal Leu (NL) or high Leu (HL) and amino acid (non-supplemented, 0.5% supplementation of Arg; ARG, 0.5% supplementation of Val; VAL, and ARG & VAL combination group; COM). All data for each response were statistically analyzed three-way ANOVA with Tukey’s post-hoc test. EM challenge decreased (P<0.05) growth performance, lean mass and percentage, and crypt depth in the jejunum, gene expression related to gut health such as mucin 2 (MUC2) and occluding (OCLDN), antioxidant capacity such as superoxide dismutase 1 (SOD1), catalase (CAT) and glutathione peroxidase 1 (GPX1), and protein synthesis such as mammalian target of rapamycin (mTOR) and eukaryotic translation initiation factor 4E binding protein 1 (4EBP1), while increasing (P<0.05) lesion score, FITC-d level in serum, and cytokine such as tumor necrosis factor-alpha (TNF-α), interleukin-2 (IL-2) and interleukin-10 (IL-10) compared to non-challenged groups. HL diets decreased (P<0.05) growth performance and increased (P<0.05) gene expression of mTOR compared to NL diets. Supplementation of Arg and Val (COM) improved (P<0.05) growth performance, intestinal morphology, gene expression related to gut health such as MUC2, zonula occludens 1 (ZO1), antioxidant capacity such as SOD1, and protein synthesis such as mTOR and 4EBP1, and thus mitigated (P<0.05) jejunal lesion score, release of oocyst shedding, and gene expression of TNF-α compared to non-supplemented groups. Especially, when broilers fed diets with Arg and Val, poor growth performance lean mass and crypt depth caused by E.maxima and high leucine were mitigated (P>0.05).
In conclusion, E.maxima had adverse effects on performance and gastrointestinal health, and high leucine especially negatively affected feed intake, and these parameters were improved by supplementing arginine and valine.